Climate headliners: Big snow, twisters, Christmas heat, and floods

For much of New Zealand, 2012 was a slightly cooler year than normal.
  • Image, road to the Hooker Valley covered in snow, Aoraki National Park.

    The big picture

    The west was generally sunnier and drier than average, while the east recorded near- or slightly below-average sunshine, and near- or slightly above-average rainfall.

    Wanganui and Secretary Island (in Fiordland) had their driest years on record, while Te Kuiti, New Plymouth, Paraparaumu, and Greymouth enjoyed their sunniest.

    Yet during the year, several extreme events caused considerable disruption and even claimed lives.

    Cold and windy events

    On 6 June 2012, heavy snow fell to very low levels in Canterbury, Arthur’s Pass, Otago, the West Coast, and Marlborough. Afternoon temperatures in Canterbury, Blenheim, around Arthur’s Pass, and on the West Coast set new low records for the month. In some cases, they broke all-time (any month) records. Maximum temperatures in Canterbury struggled to reach even 1°C as heavy snow fell throughout the daylight hours.

    And 2012 was a year in which people spotted 14 tornadoes or waterspouts. They included a tornado that touched down near Hobsonville, Auckland, on 6 December, which tragically killed three people.

    Rare, hot events

    Heatwaves and extreme high temperatures were generally lacking in 2012. In January and February, cloudy and wet conditions meant the typical summertime swelter was absent.

    However, later in the year, between 22 and 27 December, ex-tropical cyclone Evan slowly approached the northern North Island, dragging very warm and humid subtropical air onto the country. Humidity levels were very high over the North Island during this period. The north-east air stream also produced extremely high Christmas Day and Boxing Day temperatures in Nelson, Wairarapa, and in western areas from Taranaki to Wellington, which were in the lee of the main ranges. Wellington’s Christmas Day maximum of 28.6°C fell just 0.1°C short of the city’s highest Christmas Day temperature on record (in 1934). Elsewhere, numerous extreme maximum temperature records occurred in the week around Christmas, due to warm, windy, north-westerly conditions.

    Wet and windy events

    Eight particularly notable rainfall events happened during 2012. On 22 and 23 February, heavy rain caused flooding and slips in Otago, Nelson, and the central North Island. A weather 'bomb' during 3–4 March caused heavy rain and extremely strong winds for the western and southern North Island and Nelson. On 19 March, widespread flooding affected Northland when a deep low stalled east of the Bay of Islands. This low moved south over the North Island on 20 March, bringing wind and rain that almost isolated Gisborne as slips and fallen trees blocked many roads.

    On 5 June, the north-west South Island was affected by record-breaking rain associated with a rapidly deepening low over the Tasman Sea. On 16 July, flooding was widespread in many regions over the southern half of the North Island and the northern South Island. Westport was isolated, and state highways were closed due to slips and floodwaters. Back-to-back events on 23 and 30 July flooded the western Bay of Plenty and Coromandel. And several heavy rain events from 1 to 15 August flooded parts of Marlborough, Canterbury, and North Otago. 

    Source: NIWA

New Zealand’s most damaging and lethal tornado occurred in 1948 in Hamilton.

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